The present invention relates generally to a rear axle assembly of a work machine, and more particularly to an apparatus and method for controlling the temperature of fluid in a rear axle assembly.
Work machines, such as mining trucks, typically include a rear axle assembly which powers the rear tires and supports the rear of the machine. The rear axle assembly includes a left wheel group, a right wheel group, and a rear axle housing. The rear axle assembly mechanically couples the right and left wheel groups. This rear axle assembly allows the right and left wheels to rotate at different speeds relative to one another as the work machine is driven in a curved path.
The rear axle assembly has an internal component chamber which houses a number of components. For example, one internal component chamber houses side gears and pinion gears. Adequate lubrication of the aforementioned components by a fluid, such as oil, is an important factor in maintaining the proper operation of the rear axle assembly. For example, the oil contained within the rear axle assembly must adequately lubricate the right wheel group and the left wheel group in order for the work machine to operate properly.
Moreover, having the oil within an appropriate predetermined temperature range is also an important factor in maintaining the proper operation of the rear axle assembly. For example, during cold start up conditions the oil contained within the internal component chamber must be heated to be within the appropriate predetermined temperature range. On the other hand, once the work machine begins performing various work functions, the oil must be cooled such that the oil is maintained within the predetermined temperature range.
Some rear axle assembly designs maintain a level of oil in the internal component chambers such that the gears contained therein are continuously in contact with the oil pooled therein. Having the gears in contact with the pooled oil results in the oil being heated due to the physical interaction between the oil and the gears. Specifically, the rotation of the gears through the pool of oil causes the temperature of the oil to rise. While rotating the gears through the pool of oil is an effective method of heating the oil, it also requires a significant amount of power. Therefore, having the gears contained within the internal component chamber of the rear axle assembly continuously in contact with a pool of oil results in the work machine losing a significant amount of horse power as the gears are rotated through the oil. This is particularly true when the gears being rotated through the pool of oil are relatively large as is the case with mining trucks.
What is needed, therefore, is an apparatus and method for controlling the temperature or chamber level of fluid in a rear axle assembly which overcomes the above-mentioned drawback.
In accordance with a first embodiment of the present invention, there is provided an apparatus for controlling temperature of fluid in a rear axle assembly. The apparatus includes a rear axle housing having a number of sidewalls which collectively define an internal component chamber. The internal component chamber has a rear axle sump located therein, and the rear axle sump has a sump input port defined therein. The apparatus also includes a temperature control operational pressure source coupled to the internal component chamber of the rear axle housing to advance fluid therefrom. The apparatus further includes a diverter valve coupled to the temperature control operational pressure source to receive fluid advanced from the internal component chamber by the temperature control operational pressure source. The diverter valve has a cold fluid output port and a hot fluid output port. The apparatus includes a heating fluid return line interposed between the cold fluid output port of the diverter valve and the sump input port of the rear axle sump, and includes a cooling fluid return line interposed between the hot fluid output port of the diverter valve and a housing input port of the wheel group filters. The temperature control operational pressure source is selectively operable between (i) a first rate mode in which it advances fluid from the internal component chamber of the rear axle housing to the internal component chamber of the rear axle assembly at a first flow rate, and (ii) a second rate mode in which it advances fluid from the internal component chamber of the rear axle housing to the internal component chambers of the wheel groups. Additionally, the diverter valve is selectively operable between (i) a heating position in which fluid advanced by said temperature control operational pressure source is diverted to said rear axle sump of said rear axle housing via said heating fluid return line, and (ii) a cooling position in which fluid advanced by said temperature control operational pressure source is diverted to said housing input port of said rear axle housing via said cooling fluid return line.
In accordance with a second embodiment of the present invention, there is provided an apparatus for controlling temperature of fluid in a rear axle assembly. The apparatus includes a rear axle housing having a number of sidewalls which collectively define an internal component chamber. The internal component chamber has a rear axle sump located therein, and the rear axle sump has a sump input port defined therein. The apparatus also includes a temperature control operational pressure source coupled to the internal component chamber of the rear axle housing to advance fluid therefrom. The apparatus further includes a diverter valve coupled to the temperature control operational pressure source to receive fluid advanced from the internal component chamber by the temperature control operational pressure source. The diverter valve has a cold fluid output port and a hot fluid output port. The apparatus includes a heating fluid return line interposed between the cold fluid output port of the diverter valve and the sump input port of the rear axle sump, and includes a cooling fluid return line interposed between said hot fluid output port of said diverter valve and a housing input port of the rear axle housing. The housing input port of the rear axle housing is in fluid communication with a is wheel group assemblies. Additionally, the temperature control operational pressure source is selectively operable between (i) a mode in which it advances fluid to a left wheel group and a right wheel group and (ii) a mode in which it advances fluid to a sump. Also, the diverter valve is selectively operable between (i) a heating position in which fluid advanced by the temperature control operational pressure source is diverted to the rear axle sump of the rear axle housing via the heating fluid return line, and (ii) a cooling position in which fluid advanced by the temperature control operational pressure source is diverted to the housing input port of the wheel groups via the cooling fluid return line.
In accordance with a third embodiment of the present invention there is provided a method of controlling temperature of fluid in a rear axle housing. The method includes the steps of determining temperature of fluid in an internal component chamber of the rear axle housing; diverting fluid to a location within a rear axle sump positioned within the internal component chamber of the rear axle housing when the temperature has a first predetermined relation with a first temperature threshold; diverting fluid to a housing input port of the wheel group housings when the temperature does not have the first predetermined relation with the first temperature threshold; advancing fluid from said internal component chamber of the rear axle housing at a first flow rate when the temperature has a second predetermined relation with a second temperature threshold; and advancing fluid from the internal component chamber of the rear axle housing at a second flow rate when the temperature does not have the second predetermined relation with the second temperature threshold.
In accordance with a fourth embodiment of the present invention there is provided a method of controlling temperature of fluid in a rear axle housing of a vehicle. The method includes the steps of determining a velocity of the vehicle; determining temperature of fluid in an internal component chamber of the rear axle housing; diverting fluid to or from a location within a rear axle sump positioned within the internal component chamber of the rear axle housing when the temperature has a first predetermined relation with a first temperature threshold; diverting fluid to a housing input port of the wheel group housing when the temperature does not have the first predetermined relation with the first temperature threshold; advancing fluid from the internal component chamber of the rear axle housing when (i) the temperature has a second predetermined relation with a second temperature threshold while (ii) the velocity has a third predetermined relation with a velocity threshold; and advancing fluid from the internal component chamber of the rear axle housing when (i) the temperature does not have a second predetermined relation with a second temperature threshold while (ii) the velocity has a third predetermined relation with a velocity threshold.